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         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12863       4957 
2000        37960      15676 
2001        39112      15166 
2002        35428      15298 
2003        57953      24009 
2004        45256      17390 
2005        79811      24593 
2006       102757      33049 
2007       187241      58066 
2008       105970      30461 
2009        88887      25112 
2010       141157      37967 
2011       150026      41670 
2012       140888      39094 
2013       214302      61112 
2014       544726     138642 
2015       796060     209512 
2016       645012     167465 
2017       542822     146980 
2018       337155      94798 
2019       848583     207214 
2020       589946     149629 
2021       800650     189362 
2022       606664     173666 
2023       546562     156408 
2024       604451     173674 
2025       531376     151352