To calculate the weekly return of each stock and standard deviation of each stock as at end of December 2020

Date	Open	High	Low	Close	Adj Close	Volume
1/1/2020	3.30	3.36	3.28		0.315586	13000
1/2/2020	2.90	2.95	2.82		0.345172	61300
1/3/2020	2.70	2.74	2.61		0.305724	7050
1/4/2020	2.07	2.19	2.03		0.325448	2920
1/5/2020	2.35	2.40	2.23		0.310655	45100
1/6/2020	2.66	2.77	2.46		0.281069	2811
1/7/2020	2.58	2.61	2.48		0.281069	62300
1/8/2020	2.28	2.29	2.20		0.295862	20174
1/9/2020	2.30	2.37	2.21		0.286	96709
1/10/2020	2.05	2.13	2.04		0.300793	23990
1/11/2020	2.40	2.11	2.14		0.243490	30900
1/12/2020	2.60	2.52	2.25		0.90200	39000