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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2894       1012 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12857       4955 
2000        37953      15673 
2001        39092      15157 
2002        34864      15109 
2003        56770      23612 
2004        45224      17377 
2005        79788      24586 
2006       102704      33033 
2007       187101      58028 
2008       105624      30367 
2009        88751      25077 
2010       141062      37941 
2011       149675      41574 
2012       140519      38995 
2013       214108      61058 
2014       543935     138428 
2015       795946     209488 
2016       639609     165625 
2017       542507     146883 
2018       336483      94610 
2019       849082     207375 
2020       588958     149343 
2021       799722     189101 
2022       606051     173499 
2023       546173     156298 
2024       603882     173510 
2025       532861     151938