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         1421        526 
1994         2317        836 
1995         3365       1170 
1996         3576       1256 
1997         2326        793 
1998        23248       9802 
1999        14517       5566 
2000        40432      16776 
2001        42988      16670 
2002        32435      14498 
2003        61088      25329 
2004        47885      18366 
2005        85082      26160 
2006       110520      35319 
2007       203415      62406 
2008       124647      35484 
2009       101189      28443 
2010       117796      32726 
2011       176368      48775 
2012       163943      45333 
2013       253807      71795 
2014       603911     154622 
2015       728920     193301 
2016       716224     185002 
2017       600232     161949 
2018       395239     110748 
2019       929078     228106 
2020       682687     174855 
2021       892197     213520 
2022       662536     189491 
2023       601081     173069 
2024       250135      72461