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          465        177 
1992          732        297 
1993         1283        478 
1994         1643        604 
1995         2936       1026 
1996         2936       1038 
1997         1801        624 
1998        21533       9162 
1999        13020       5012 
2000        38186      15780 
2001        39083      15176 
2002        30536      13684 
2003        57037      23754 
2004        45771      17577 
2005        80444      24784 
2006       103716      33333 
2007       189661      58713 
2008       109321      31360 
2009        91169      25718 
2010       142905      38422 
2011       153730      42674 
2012       145242      40279 
2013       217145      61914 
2014       556410     141746 
2015       796109     209393 
2016       652920     169602 
2017       548401     148436 
2018       344351      96791 
2019       856407     208963 
2020       604607     153679 
2021       814362     193113 
2022       612655     175391 
2023       552543     158116 
2024       606798     174705 
2025       413170     119133