Table:
Historical population
Year	Pop.	±%
1850	1,592	—
1860	1,565	−1.7%
1870	1,628	+4.0%
1880	1,897	+16.5%
1890	2,093	+10.3%
1900	2,152	+2.8%
1910	2,326	+8.1%
1920	2,575	+10.7%
1930	2,808	+9.0%
1940	2,875	+2.4%
1950	3,389	+17.9%
1960	5,923	+74.8%
1970	10,107	+70.6%
1980	11,358	+12.4%
1990	11,912	+4.9%
2000	13,164	+10.5%
2010	13,879	+5.4%
2017	14,814	+6.7%
* = population estimate.
Source: United States census records and Population Estimates Program data.[3][4][5][6][7][8][9][10][11][12]

Could you calculate the row number and column number in this table? Present the final answer in a JSON format {"row_number": "m", "column_number": "n"} such as {"row_number": "2", "column_number": "3"}.

This table has 21 rows and 3 columns. Thus, the final answer is {"row_number": "21", "column_number": "3"}.