what is the average money spent per unit volume for each stock
trade_id	stock_symbol	trade_date	trade_price	trade_volume
1	MSFT	6/12/20	132.84	81289
2	TSLA	4/28/20	678.8	39683
3	AMZN	11/23/21	784.9	71734
4	AAPL	10/25/20	775.77	76454
5	TSLA	1/26/21	408.67	19482
6	TSLA	1/27/20	524.18	33402
7	TSLA	3/11/21	954.74	25222
8	AMZN	10/22/20	703.86	98087
9	TSLA	8/22/20	403.06	70036
10	TSLA	8/20/20	451.59	98
11	GOOGL	9/6/20	391.4	49344
12	MSFT	3/20/21	523.53	39070
13	AMZN	4/7/21	42.79	76508
14	MSFT	1/21/20	73.89	7615
15	TSLA	7/30/20	940.77	95926
16	GOOGL	3/12/20	492.19	65070
17	AMZN	5/28/20	765.51	56402
18	AMZN	6/23/20	972.78	97105
19	AAPL	9/29/21	388.2	47166
20	AMZN	5/3/21	827.83	68678
21	GOOGL	4/6/21	344.63	43794
22	GOOGL	12/4/21	759.39	87281
23	GOOGL	3/26/20	439.77	95060
24	GOOGL	5/21/20	342.37	55142
25	TSLA	12/20/21	666.65	88852
26	GOOGL	3/20/20	363	35438
27	MSFT	7/12/20	398.56	83743
28	TSLA	11/1/21	208.78	9481
29	AAPL	3/24/21	767.12	91071
30	MSFT	2/16/21	95.02	7749