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          724        294 
1993         1283        478 
1994         1640        603 
1995         2912       1018 
1996         2904       1027 
1997         1796        622 
1998        21472       9137 
1999        12936       4983 
2000        38087      15734 
2001        39766      15398 
2002        31400      13959 
2003        56595      23584 
2004        45514      17484 
2005        80117      24687 
2006       103178      33174 
2007       188380      58373 
2008       107539      30886 
2009        90089      25432 
2010       141981      38182 
2011       151870      42172 
2012       143116      39700 
2013       215763      61526 
2014       550714     140224 
2015       793760     208805 
2016       648542     168421 
2017       545385     147613 
2018       340397      95688 
2019       851683     207815 
2020       596811     151523 
2021       807391     191188 
2022       609564     174513 
2023       549830     157353 
2024       605968     174214 
2025       473367     135268