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          503        190 
1992          936        367 
1993         1669        610 
1994         2326        839 
1995         3790       1313 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14542       5577 
2000        40506      16809 
2001        43109      16719 
2002        32581      14566 
2003        61376      25443 
2004        48113      18455 
2005        85755      26360 
2006       111180      35517 
2007       204955      62822 
2008       126015      35850 
2009       102549      28811 
2010       119116      33070 
2011       178831      49453 
2012       165975      45926 
2013       256825      72895 
2014       641475     163314 
2015       745458     197389 
2016       573574     153037 
2017       611123     163859 
2018       414264     114266 
2019       942492     230679 
2020       693454     177843 
2021       900481     215679 
2022       668478     191198 
2023       608975     175318 
2024       199852      57497