diff --git a/core/models/survex.py b/core/models/survex.py
index ea7f617..acf29f0 100644
--- a/core/models/survex.py
+++ b/core/models/survex.py
@@ -246,6 +246,12 @@ class SurvexBlock(models.Model):
 
     def isSurvexBlock(self):  # Function used in templates
         return True
+        
+    def year(self):
+        if self.date:
+            return self.date.year
+        else:
+            return 1970
 
     def DayIndex(self):
         """This is used to set different colours for the different trips on
diff --git a/core/views/scans.py b/core/views/scans.py
index 4263c2c..225f18e 100644
--- a/core/views/scans.py
+++ b/core/views/scans.py
@@ -1,4 +1,5 @@
 import datetime
+from collections import defaultdict
 from pathlib import Path
 from urllib.parse import unquote as urlunquote
 
@@ -327,14 +328,25 @@ def cavewallets(request, caveid):
 
     expeditions = Expedition.objects.all()
     length_ug = 0.0
+    length_by_year = defaultdict(int) # initialises values to zero
+    checksum = 0
     for w in manywallets:
         for sb in w.survexblock_set.all():
             length_ug += sb.legslength    
+            length_by_year[sb.year()] += sb.legslength
+    length_by_year = dict(sorted(length_by_year.items())) 
+    for y in length_by_year:
+        checksum += length_by_year[y]
+        print(f"{y} {length_by_year[y]:.0f}")
+    for key in list(length_by_year.keys()):
+        if length_by_year[key] < 0.1:
+            del length_by_year[key]
+            
     return render(
         request,
         "cavewallets.html",
         {"manywallets": manywallets, "settings": settings, "cave": cave, "expeditions": expeditions,
-        "length_ug": length_ug, "year": current_expo()}
+        "length_ug": length_ug, "length_by_year": length_by_year, "checksum": checksum, "year": current_expo()}
     )
 
 
diff --git a/templates/cavewallets.html b/templates/cavewallets.html
index ace826d..a469242 100644
--- a/templates/cavewallets.html
+++ b/templates/cavewallets.html
@@ -25,7 +25,11 @@ traced to produce Tunnel or Therion drawings and eventually the final complete c
 
 
 <br />
-<p>Total underground survey length: {{length_ug|floatformat:"1g"}} m<br />
+  {% for year, length in length_by_year.items %}
+    {{ year }}  {{ length|floatformat:"0g" }} m</br>
+    {% endfor %}
+
+<p>Total underground survey length: {{length_ug|floatformat:"1g"}} m (checksum: {{length_ug|floatformat:"1g"}} )<br />
 Note that this is for <em>all the wallets</em> listed above, which includes those which are surveys of different caves not just {{cave}}.
 <br />
 If you want accurate cave lengths for {{cave}}, go to the <a href="/survexfile/{{cave.survex_file}}">primary survex file</a> for this cave 
diff --git a/templates/wallet_table.html b/templates/wallet_table.html
index ba39c05..7989f8e 100644
--- a/templates/wallet_table.html
+++ b/templates/wallet_table.html
@@ -62,5 +62,4 @@ which is probably more useful.
 
 <p>Note that names in italics are copied from the related survex file block name.<br />
 Note also that survex data recently uploaded will not appear in this table until a database reset is done on the server.
-<p>Note that all the Tunneled/Therioned boxes are fuchsia pending a proper method of setting this.