Table 2. Attributes of the standard deviation ellipse for cultivated land.

	Standard deviation of the major axis	Standard deviation of the major axis	Central coordinates	Axis ratio
1990	106,501.93	44,217.34	29°28′48″N, 103°48′44″E	0.42
1995	110,793.02	39,451.13	29°34′14″N, 103°45′51″E	0.36
2000	112,807.27	43,013.45	29°33′29″N, 103°48′55″E	0.38
2005	121,953.49	44,472.10	29°41′04″N, 103°45′58″E	0.36
2010	119,379.96	440,35.97	29°41′10″N, 103°47′41″E	0.37
2015	119,422.45	43,864.60	29°44′24″N, 103°46′21″E	0.37
2020	118,852.37	45,072.74	29°44′47″N, 103°48′22″E	0.38