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         1356        504 
1994         2266        818 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23237       9798 
1999        14511       5564 
2000        40406      16765 
2001        42963      16660 
2002        32426      14494 
2003        61039      25311 
2004        47854      18355 
2005        84897      26106 
2006       110361      35271 
2007       203103      62322 
2008       124385      35410 
2009       100940      28375 
2010       117529      32656 
2011       175896      48647 
2012       163629      45249 
2013       252857      71534 
2014       602845     154356 
2015       727715     192968 
2016       712286     184164 
2017       599424     161786 
2018       394479     110546 
2019       928846     228062 
2020       689802     176366 
2021       891535     213331 
2022       662042     189344 
2023       599681     172673 
2024       260543      75483