Find the Monthy returns for AAPL and SP500

	Monthly Prices			Monthly Returns
Date	AAPL	SP500		AAPL	SP500
5/1/2018	45.072868	2,705.27
6/1/2018	44.820538	2,718.37
7/1/2018	46.07476	2,816.29
8/1/2018	55.115868	2,901.52
9/1/2018	54.849937	2,913.98
10/1/2018	53.178249	2,711.74
11/1/2018	43.391079	2,760.17
12/1/2018	38.46114	2,506.85
1/1/2019	40.582428	2,704.10
2/1/2019	42.218506	2,784.49
3/1/2019	46.513416	2,834.40
4/1/2019	49.138439	2,945.83
5/1/2019	42.869724	2,752.06
6/1/2019	48.65168	2,941.76
7/1/2019	52.368397	2,980.38
8/1/2019	51.311405	2,926.46
9/1/2019	55.264339	2,976.74
10/1/2019	61.381241	3,037.56
11/1/2019	65.943619	3,140.98
12/1/2019	72.675339	3,230.78
1/1/2020	76.600517	3,225.52
2/1/2020	67.653778	2,954.22
3/1/2020	63.083504	2,584.59
4/1/2020	72.885025	2,912.43
5/1/2020	78.873604	3,044.31
6/1/2020	90.743469	3,100.29
7/1/2020	105.728088	3,271.12
8/1/2020	128.394058	3,500.31
9/1/2020	115.438042	3,363.00
10/1/2020	108.510361	3,269.96
11/1/2020	118.667633	3,621.63
12/1/2020	132.49202	3,756.07
1/1/2021	131.763107	3,714.24
2/1/2021	121.079071	3,811.15
3/1/2021	122.150002	3,972.89
4/1/2021	134.320007	4,180.17