Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          659        271 
1993         1176        442 
1994         1490        556 
1995         2377        839 
1996         2649        940 
1997         2518        860 
1998        23977       8567 
1999        12889       4913 
2000        36461      14978 
2001        41533      16314 
2002        35101      15022 
2003        57212      23432 
2004        45062      17163 
2005       303909     136904 
2006       331135     147830 
2007       192336      59563 
2008       108562      30958 
2009        89195      24946 
2010       137023      36487 
2011       144120      39211 
2012       171753      37319 
2013       226424      57024 
2014       473865     117607 
2015       714481     186889 
2016       601828     155530 
2017       507604     138041 
2018       303150      85722 
2019       807220     197821 
2020       530324     134461 
2021       715507     167637 
2022       555779     159388 
2023       512066     146697 
2024       552450     158788 
2025       526749     149458 
2026       325864      75620