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         1630        597 
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        61129      25345 
2004        47914      18376 
2005        85224      26204 
2006       110656      35361 
2007       203668      62474 
2008       124847      35540 
2009       101517      28532 
2010       118033      32788 
2011       176892      48920 
2012       164297      45430 
2013       254707      72045 
2014       604744     154844 
2015       730251     193649 
2016       710639     183583 
2017       600729     162063 
2018       395879     110927 
2019       928166     227794 
2020       684570     175379 
2021       893320     213823 
2022       663357     189734 
2023       602360     173432 
2024       243764      70588