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          489        185 
1992          764        308 
1993         1356        504 
1994         1746        640 
1995         3282       1142 
1996         3072       1085 
1997         2288        782 
1998        23066       9732 
1999        14401       5521 
2000        39945      16560 
2001        40681      15847 
2002        31932      14279 
2003        59580      24756 
2004        47195      18109 
2005        82849      25488 
2006       106716      34210 
2007       195375      60251 
2008       117243      33470 
2009        96659      27213 
2010       111253      31019 
2011       164500      45583 
2012       155630      43103 
2013       229206      65247 
2014       552959     141761 
2015       715301     188595 
2016       660671     171409 
2017       567939     153471 
2018       364703     102376 
2019       886697     216518 
2020       637819     162562 
2021       858427     204429 
2022       637784     182557 
2023       577708     165444 
2024       607095     174963