when did the nba start keeping track of possessions by a team

The Boston Celtics have 645,079.2 possessions all-time.

	TEAM	POSS	GP	MPG	PPG	RPG	APG	SPG	BPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	TS%	OREB	DREB	MIN	PTS	REB	AST	STL	BLK	PF
1	Celtics	645,079.2	6,201	241.6	105.4	50.3	23.8	8.1	4.8	40.3	90.5	44.6	6.2	17.5	35.7	21.0	27.7	75.8	51.4	12.2	31.7	1,498,265	653,807	299,793	147,662	33,968	20,367	144,414
2	Stags	25,289.3	237	241.6	79.0		14.6			30.3	95.5	31.7				18.5	27.7	66.6	36.7			57,255	18,727		3,454			6,319
3	Rebels	6,217.2	60	242.1	70.9		8.2			27.9	95.0	29.4				15.1	23.8	63.2	33.6			14,525	4,251		494			1,246
4	Falcons	6,299	60	240.4	63.3		8.0			24.0	97.4	24.6				15.4	24.9	61.8	29.2			14,425	3,797		482			1,351
5	Knicks	627,266.6	6,191	241.9	102.2	47.9	22.2	7.9	4.3	39.0	87.7	44.5	5.9	16.7	35.4	20.6	27.7	74.5	51.2	12.2	30.5	1,497,665	632,827	285,028	137,733	33,105	18,208	149,013
6	Warriors	648,544.8	6,192	241.6	105.9	50.2	23.5	8.8	5.1	40.5	91.3	44.3	6.5	18.0	36.2	21.0	28.4	74.1	51.0	13.3	31.1	1,495,780	655,756	299,034	145,603	36,885	21,212	145,776
7	Ironmen	5,502.5	60	240.8	61.2		4.5			22.4	82.7	27.1				16.4	25.1	65.3	32.7			14,450	3,674		272			1,360
8	Steam Rollers	17,444.3	168	241.6	73.7		11.0			27.7	93.1	29.7				18.3	27.9	65.8	35.0			40,595	12,375		1,854			3,669
9	Bombers	23,023.8	237	242.4	72.0		12.9			26.6	86.0	30.9				18.8	27.7	67.9	36.7			57,455	17,053		3,064			5,360
10	Huskies	6,201.9	60	240.4	66.6		7.7			25.3	94.5	26.7				16.1	25.9	62.2	31.4			14,425	3,996		463			1,271
11	Capitols	27,600.1	271	241.3	77.2	43.8	12.2			28.0	90.2	31.1				21.2	28.8	73.5	37.5			65,390	20,920	1,534	3,296			6,825
12	Bullets	43,685.6	450	242.2	79.8	52.4	18.2			28.2	82.6	34.2				23.4	32.7	71.5	41.2			108,970	35,901	14,367	8,170			11,975
13	Pistons	617,370.8	6,085	241.6	102.4	48.4	22.0	7.8	4.9	39.0	88.3	44.2	5.4	15.5	34.8	21.1	28.5	74.0	50.8	13.0	30.3	1,470,050	623,199	288,099	134,146	32,793	20,571	143,046
14	Jets	6,086.4	60	240.4	74.7		20.4			27.0	89.5	30.2				20.7	30.0	69.0	36.4			14,425	4,482		1,225			1,393
15	Lakers	627,564.6	6,091	241.7	106.7	49.2	24.1	8.3	5.5	40.8	89.0	45.8	5.8	16.7	34.7	21.6	29.0	74.5	52.4	12.5	31.7	1,472,390	650,019	293,605	146,749	34,773	23,072	137,307
16	Kings	627,414.2	6,092	241.7	105.1	47.8	23.6	8.2	4.6	40.1	88.8	45.2	5.7	15.9	35.6	21.4	28.5	75.0	51.8	12.3	30.6	1,472,455	640,232	285,318	143,988	34,511	19,265	145,446
17	Packers	7,228.4	64	244.3	87.3		19.4			30.4	97.7	31.1				26.6	36.6	72.7	38.4			15,635	5,589		1,240			1,806
18	Nuggets	6,055.8	62	240.0	77.7		16.8			27.9	83.6	33.4				21.9	32.2	67.8	39.7			14,880	4,817		1,044			1,692
19	Olympians	25,608.8	269	242.6	81.1	45.8	20.0			29.5	81.0	36.4				22.1	30.8	71.8	42.9			65,260	21,817	9,393	5,368			6,596
20	Red Skins	6,076.7	62	240.0	82.4		20.6			27.9	81.0	34.4				26.7	37.7	70.7	42.2			14,880	5,108		1,279			1,766
21	76ers	621,917.7	6,027	241.7	104.8	48.7	22.8	8.8	5.5	39.5	88.3	44.7	5.1	14.8	34.4	22.6	30.1	75.1	51.6	12.7	30.7	1,456,855	631,400	290,690	137,422	36,766	22,982	140,241
22	Hawks	610,460.7	6,025	241.6	103.2	48.4	22.8	8.3	5.0	39.0	87.5	44.5	5.7	16.4	35.0	21.7	29.0	74.8	51.5	13.0	30.3	1,455,495	621,935	288,342	137,526	34,962	21,180	142,432
23	Hawks	5,818.4	62	240.8	79.4		21.4			28.2	79.1	35.6				23.0	32.3	71.4	42.5			14,930	4,921		1,324			1,780
24	Wizards	527,100.5	5,174	241.6	104.8	46.8	22.8	7.9	5.0	40.7	89.1	45.6	5.1	14.8	34.4	19.9	26.8	74.3	52.0	12.5	30.7	1,250,185	542,486	241,905	118,142	33,260	20,899	117,121
25	Bulls	470,372.6	4,766	241.8	103.0	45.4	23.8	8.0	4.8	39.6	86.4	45.9	5.2	14.8	35.4	19.6	25.9	75.8	52.6	12.8	31.1	1,152,490	490,747	216,322	113,589	33,413	20,228	106,365