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          492        186 
1992          770        310 
1993         1356        504 
1994         1960        714 
1995         3339       1161 
1996         3562       1251 
1997         2320        791 
1998        23173       9774 
1999        14481       5552 
2000        40131      16643 
2001        45289      17407 
2002        32127      14370 
2003        60338      25045 
2004        47548      18238 
2005        83844      25792 
2006       108465      34721 
2007       199562      61372 
2008       120997      34488 
2009        98865      27814 
2010       114376      31831 
2011       169576      46948 
2012       159374      44110 
2013       239421      68041 
2014       581977     149475 
2015       704466     186847 
2016       678036     176058 
2017       576757     155966 
2018       377869     105977 
2019       904252     221257 
2020       653367     166801 
2021       871695     207869 
2022       646406     185077 
2023       594518     170000 
2024       370677     107787