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          730        296 
1993         1283        478 
1994         1643        604 
1995         2921       1021 
1996         2921       1033 
1997         1801        624 
1998        21495       9145 
1999        12970       4995 
2000        38137      15758 
2001        39173      15200 
2002        32202      14233 
2003        56841      23677 
2004        45622      17524 
2005        80281      24734 
2006       103429      33248 
2007       188960      58528 
2008       108548      31155 
2009        90594      25567 
2010       142435      38299 
2011       152834      42431 
2012       144195      39991 
2013       216556      61754 
2014       553697     141024 
2015       793694     208755 
2016       650345     168911 
2017       546780     147990 
2018       342443      96258 
2019       853682     208274 
2020       600666     152602 
2021       810839     192125 
2022       611125     174953 
2023       551376     157785 
2024       610616     175358 
2025       460093     130985