Question: 对于2024年08月19日-2025年04月04日的贝塔系数，中国中车的值是？使用不复权价格，写出指标公式，搜集原始数据，计算得出答案，保留四位小数。注意列出原始数据和关键计算过程。
Formula: \beta = cov(r, r_m) / var(r_m)
Data:
date,close,market_close
2024-08-16,7.62,3345.63
2024-08-19,8.02,3356.97
2024-08-20,7.92,3332.7
2024-08-21,7.94,3321.64
2024-08-22,8.05,3313.14
2024-08-23,8.09,3327.19
2024-08-26,7.68,3324.22
2024-08-27,7.45,3305.33
2024-08-28,7.32,3286.5
2024-08-29,7.26,3277.68
2024-08-30,7.14,3321.43
2024-09-02,6.91,3265.01
2024-09-03,6.92,3273.43
2024-09-04,6.88,3252.16
2024-09-05,6.89,3257.76
2024-09-06,6.83,3231.35
2024-09-09,6.72,3192.95
2024-09-10,6.74,3195.76
2024-09-11,6.67,3186.13
2024-09-12,6.83,3172.47
2024-09-13,6.78,3159.25
2024-09-18,6.86,3171.01
2024-09-19,6.89,3196.04
2024-09-20,6.85,3201.05
2024-09-23,7.02,3212.76
2024-09-24,7.31,3351.91
2024-09-25,7.52,3401.53
2024-09-26,7.63,3545.32
2024-09-27,7.65,3703.68
2024-09-30,8.17,4017.85
2024-10-08,8.6,4256.1
2024-10-09,7.95,3955.98
2024-10-10,8.51,3997.79
2024-10-11,8.06,3887.17
2024-10-14,8.28,3961.34
2024-10-15,8.13,3855.99
2024-10-16,8.09,3831.59
2024-10-17,7.98,3788.22
2024-10-18,8.17,3925.23
2024-10-21,8.18,3935.2
2024-10-22,8.21,3957.78
2024-10-23,8.25,3973.21
2024-10-24,8.27,3928.83
2024-10-25,8.16,3956.42
2024-10-28,8.25,3964.16
2024-10-29,8.32,3924.65
2024-10-30,8.36,3889.45
2024-10-31,8.32,3891.04
2024-11-01,8.46,3890.02
2024-11-04,8.49,3944.76
2024-11-05,8.55,4044.57
2024-11-06,8.66,4024.28
2024-11-07,8.82,4145.7
2024-11-08,8.6,4104.05
2024-11-11,8.43,4131.13
2024-11-12,8.21,4085.74
2024-11-13,8.35,4110.89
2024-11-14,8.26,4039.62
2024-11-15,8.13,3968.83
2024-11-18,8.37,3950.38
2024-11-19,8.17,3976.89
2024-11-20,8.15,3985.77
2024-11-21,8.17,3989.3
2024-11-22,7.93,3865.7
2024-11-25,7.87,3848.09
2024-11-26,7.81,3840.18
2024-11-27,7.95,3907.04
2024-11-28,7.88,3872.55
2024-11-29,7.93,3916.58
2024-12-02,8.16,3947.63
2024-12-03,8.25,3951.89
2024-12-04,8.2,3930.56
2024-12-05,8.23,3921.59
2024-12-06,8.28,3973.14
2024-12-09,8.37,3966.57
2024-12-10,8.42,3995.64
2024-12-11,8.38,3988.83
2024-12-12,8.35,4028.5
2024-12-13,8.03,3933.18
2024-12-16,8.0,3911.84
2024-12-17,8.16,3922.03
2024-12-18,8.24,3941.89
2024-12-19,8.14,3945.46
2024-12-20,8.08,3927.74
2024-12-23,8.09,3933.57
2024-12-24,8.38,3983.69
2024-12-25,8.37,3985.63
2024-12-26,8.25,3987.48
2024-12-27,8.35,3981.03
2024-12-30,8.37,3999.05
2024-12-31,8.38,3934.91
2025-01-02,7.96,3820.4
2025-01-03,7.83,3775.16
2025-01-06,7.7,3768.97
2025-01-07,7.65,3796.11
2025-01-08,7.64,3789.22
2025-01-09,7.54,3779.88
2025-01-10,7.47,3732.48
2025-01-13,7.4,3722.51
2025-01-14,7.53,3820.54
2025-01-15,7.47,3796.03
2025-01-16,7.45,3800.38
2025-01-17,7.47,3812.34
2025-01-20,7.43,3829.68
2025-01-21,7.42,3832.61
2025-01-22,7.32,3797.02
2025-01-23,7.38,3803.74
2025-01-24,7.45,3832.86
2025-01-27,7.44,3817.08
2025-02-05,7.33,3795.08
2025-02-06,7.37,3842.83
2025-02-07,7.46,3892.7
2025-02-10,7.48,3901.06
2025-02-11,7.4,3883.14
2025-02-12,7.45,3919.86
2025-02-13,7.41,3905.14
2025-02-14,7.54,3939.01
2025-02-17,7.55,3947.4
2025-02-18,7.55,3912.78
2025-02-19,7.55,3940.16
2025-02-20,7.42,3928.9
2025-02-21,7.56,3978.44
2025-02-24,7.63,3969.72
2025-02-25,7.51,3925.65
2025-02-26,7.54,3959.94
2025-02-27,7.59,3968.12
2025-02-28,7.48,3890.05
2025-03-03,7.5,3888.47
2025-03-04,7.52,3885.22
2025-03-05,7.55,3902.57
2025-03-06,7.57,3956.24
2025-03-07,7.59,3944.01
2025-03-10,7.44,3928.8
2025-03-11,7.4,3941.42
2025-03-12,7.33,3927.23
2025-03-13,7.28,3911.58
2025-03-14,7.52,4006.56
2025-03-17,7.43,3996.79
2025-03-18,7.41,4007.72
2025-03-19,7.43,4010.17
2025-03-20,7.39,3974.99
2025-03-21,7.31,3914.7
2025-03-24,7.3,3934.85
2025-03-25,7.38,3932.3
2025-03-26,7.41,3919.36
2025-03-27,7.38,3932.41
2025-03-28,7.3,3915.17
2025-03-31,7.06,3887.31
2025-04-01,6.98,3887.68
2025-04-02,6.93,3884.39
2025-04-03,6.91,3861.5

Indicator data:
Answer: 0.8829