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        21446       9125 
1999        12857       4955 
2000        37931      15663 
2001        39081      15152 
2002        34845      15101 
2003        56733      23597 
2004        45196      17367 
2005        79730      24568 
2006       102647      33015 
2007       186972      57992 
2008       105292      30277 
2009        88551      25024 
2010       140941      37909 
2011       149325      41477 
2012       140168      38900 
2013       213782      60970 
2014       542956     138175 
2015       795661     209427 
2016       638781     165373 
2017       542087     146769 
2018       335933      94455 
2019       849092     207431 
2020       588011     149075 
2021       798724     188854 
2022       605470     173331 
2023       545569     156126 
2024       603121     173296 
2025       554446     158225