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          532        200 
1992          936        367 
1993         1669        610 
1994         2333        842 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23332       9836 
1999        14615       5608 
2000        40723      16912 
2001        41798      16305 
2002        32938      14711 
2003        61962      25682 
2004        48655      18670 
2005        86972      26713 
2006       112661      35954 
2007       207628      63555 
2008       128521      36523 
2009       104513      29346 
2010       121476      33695 
2011       183058      50607 
2012       169728      46951 
2013       264716      75065 
2014       660431     168390 
2015       772767     204742 
2016       577906     154226 
2017       589563     157911 
2018       406486     114036 
2019       928781     226715 
2020       712359     182832 
2021       924647     222389 
2022       691918     197822 
2023       626946     180419 
2024        98376      28693