Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          492        186 
1992          770        310 
1993         1654        605 
1994         2320        837 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14522       5568 
2000        40447      16783 
2001        43012      16678 
2002        32464      14511 
2003        61142      25350 
2004        47919      18378 
2005        85233      26207 
2006       110692      35371 
2007       203715      62486 
2008       124882      35549 
2009       101571      28547 
2010       118070      32798 
2011       176962      48940 
2012       164339      45441 
2013       254860      72088 
2014       604893     154883 
2015       730403     193692 
2016       708002     182914 
2017       600836     162094 
2018       395909     110935 
2019       928722     227844 
2020       684837     175455 
2021       893450     213861 
2022       663479     189769 
2023       602521     173473 
2024       244362      70762