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         1587        582 
1994         2317        836 
1995         3368       1171 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14520       5567 
2000        40442      16781 
2001        43008      16676 
2002        32462      14510 
2003        61124      25343 
2004        47910      18375 
2005        85217      26202 
2006       110656      35361 
2007       203653      62470 
2008       124836      35537 
2009       101502      28528 
2010       118029      32787 
2011       176870      48914 
2012       164268      45422 
2013       254663      72032 
2014       604702     154833 
2015       730203     193636 
2016       712951     184134 
2017       601196     162194 
2018       395875     110925 
2019       928633     227946 
2020       687527     176031 
2021       965344     222858 
2022       663327     189726 
2023       602292     173413 
2024       243625      70551