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          444        170 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2894       1012 
1996         2895       1024 
1997         1784        618 
1998        21446       9125 
1999        12857       4955 
2000        37915      15657 
2001        39075      15149 
2002        34835      15097 
2003        56705      23585 
2004        45169      17357 
2005        79700      24559 
2006       102596      32999 
2007       186883      57969 
2008       105136      30235 
2009        88467      25001 
2010       140865      37889 
2011       149145      41429 
2012       139919      38831 
2013       213664      60938 
2014       542293     138008 
2015       795743     209456 
2016       638339     165219 
2017       541925     146726 
2018       335892      94469 
2019       848464     207295 
2020       587247     148855 
2021       797980     188658 
2022       604928     173178 
2023       545140     156003 
2024       602302     173068 
2025       560397     160074