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          468        178 
1992          737        299 
1993         1288        480 
1994         1655        608 
1995         2964       1036 
1996         2950       1043 
1997         1813        628 
1998        21568       9178 
1999        13079       5034 
2000        38313      15832 
2001        39189      15217 
2002        30699      13745 
2003        57271      23845 
2004        45951      17640 
2005        80652      24846 
2006       104017      33423 
2007       190355      58901 
2008       110429      31658 
2009        91739      25875 
2010       143643      38613 
2011       154966      43017 
2012       146653      40661 
2013       218096      62175 
2014       560394     142824 
2015       799205     210240 
2016       655916     170426 
2017       550608     149030 
2018       346969      97503 
2019       859094     209659 
2020       610111     155179 
2021       820376     194659 
2022       614931     176032 
2023       554309     158592 
2024       609097     175497 
2025       333342      95580